The present invention relates to a method of making a call connection in a private branch exchange system, and more specifically a call with whether the certain extension subscriber by utilizing a private pager system especially, in the case of a party line used by a plurality of subscribers.
Generally, a private branch exchange(PBX) system receives an incoming call from a central office line (C.O. line) or an extension line, and transmits an outgoing call to the C.O. line and the extension line.
In the case of one party line (one telephone) being used by a plurality of subscribers, when the incoming call from the C.O line or the extension line is received at the telephone used by a desired called person by switching of the PBX system, it is unable to distinguish a right called person for a call and accordingly someone has to advise the called person of the call by doing a hook-off to connect a communication path between a caller and the called person. Accordingly in a case of a subscriber being absent, a communication becomes impossible. Therefore it is necessary to consider another method for securing a rapid connection of the call and preventing the loss of the call.
With reference to FIG. 1, a conventional connection method of the call will be described as follows.
In a conventional configuration in FIG. 1, a call generated from a C.O. line subscriber 11 is transmitted to a PBX system 31 through a C.O. line exchange system 21. The PBX system 31 transmits a ring signal to a telephone of the desired called extension party from among a plurality of telephones 41 to 49 connected to the PBX system 31, through an extension line connected to the telephone selected by the C.O. line subscriber 11. At this time, in the case that the telephone of the called extension party is being a reference numeral 41, for example, the C.O. line subscriber 11 is able to communicate with an extension subscriber of the telephone 41 when the extension subscriber hooks off the telephone 41.
Similarly, a communication between the extension subscribers is performed in such a way. When an extension subscriber 49 calls the another extension subscriber 41, by hook-off of the extension subscriber telephone 41, a call of the extension subscriber 49 is connected to the extension subscriber 41 through the PBX system 31.
However, in the case that one telephone is used by a plurality of extension subscribers, it takes times to perform a call connection between a called party and a calling party and it is troublesome to distinguish the called party from the other extension subscribers using the same telephone. Therefore the call is lost, especially when the called party is absent nearby.
To prevent a loss of the call and to cope with such troublesome, there is introduced an improved conventional method of connecting the call, such as a utilizing a pager system. The pager system includes a method of display pager and a method of mimic.
In the method of display pager, an absent subscriber not only experiences a complicated procedure to transmit a return call signal after confirming a number of the calling party displayed on the pager, but also experience a loss of the call made by the calling party and, accordingly, it is impossible to perform a communication in the case of the calling party using an exclusive line of transmission such as a public telephone set.
As compared favorably with the display pager, it is convenient for a subscriber (called party) to perform a communication by putting his extension number into any one of a plurality of extension subscriber telephones in the method of the mimic even if he is absent from his designated location. But in the case that one telephone is owned by a plurality of subscribers, it is difficult to connect a call with the called party, regardless of the called subscriber's presence or absence at the designated location. That is, because it is impossible to discriminate a right called subscriber for the call when a call signal is received in such a case, the call connection between two respective subscribers is possible only after someone hooks off the telephone of the called subscriber.